The invention relates generally to the field of systems and methods for distributing postal indicia and more particularly to systems and methods for distributing postage over a public network in a manner that is secure in the case of third party interceptiont indicia which can be efficiently printed by a postal customer on items to be mailed and a system that facilitates authentication of the printed indicia.
There are several generally accepted systems for accounting for postage for items to be mailed with a postal delivery service such as the U.S. Postal Service. In one such system the postal customer purchases postal stamps from the postal delivery service which he or she affixes directly to each item to be mailed. When the postal delivery service receives the item it will need to verify that the value of the stamp or stamps on the item is sufficient for the service. Postal delivery services such as the U.S. Postal Service currently use appearance-based mechanisms to verify that the stamps are authentic and in addition to verify the value of the stamp(s) on the item and determine whether the value is sufficient. Generally stamps must be purchased by the postal customer directly or indirectly from the postal delivery service and are considered primarily useful by low-volume customers.
Higher-volume postal customers typically use other postage accounting systems. In the other systems most notably in metered systems a postal customer makes use of a meter to apply postal xe2x80x9cindicia to respective items to be mailed each indicium identifying the value of the postage applied thereto. Prior to using the meter the postal customer purchases postage from the postal delivery service representing a bulk value which may be applied to item(s) to be mailed. As each postage indicium is applied by the meter to items to be mailed the value of the postage represented by the indicium is deducted from the value remaining in the meter which value can be replenished as necessary. As with the stamp-based system, postal delivery services such as the U.S. Postal Service, uses appearance-based mechanisms to verify that the indicium on each item to be mailed is authentic and to determine whether the value represented by the indicium is sufficient.
For some time, it has been acknowledged that current appearance-based mechanisms for verifying the authenticity and value represented by postal indicia are insufficient to protect postal revenue. To address that problem, the U.S. Postal Service has been developing a specification, called the Information Based Indicia Program (xe2x80x9cIBIPxe2x80x9d), which requires each indicium to include significantly more information to detail a postage transaction than is currently required, and to require that the information be cryptographically signed so that it cannot be altered. Although this system is secure, in order to accommodate the information required, each indicium must be printed using a dense, two-dimensional barcode. A number of problems arise in connection with use of a dense two-dimensional barcode such as would be required by the IBIP. First, since the barcode is quite dense, errors can develop during scanning, particularly in connection with items which are creased or soiled. In addition, since the barcode contains a large amount of information, the time required to process the information related to each item can be significant, which can result in delays.
A further problem arises in connection with the IBIP. The IBIP contemplates that postage purchased by a postal customer be maintained in a secure special-purpose hardware device termed a Postal Security Device (xe2x80x9cPSDxe2x80x9d). The PSD maintains the security of the information which would be used in connection with the indicia required for the IBIP, most notably the value of the postage purchased by the postal customer. The PSD can enable any printer that meets the image specifications which are required of the indicia by the IBIP to print the indicia, so that the postal customer can move from one printer to another to print indicia merely by disconnecting the PSD from the one printer and connecting it to the other. While this flexibility is advantageous, it does require rental or purchase of the PSD.
The invention provides a new and improved system and method for distributing postage over a public network in a manner that is secure in the case of third party interception, indicia which can be efficiently printed by a postal customer on items to be mailed, and a system that facilitates authentication of the printed indicia.
In brief summary, the invention provides a system for distributing postage over a public network in a manner that is secure in the case of third party interception, indicia which can be efficiently printed by a postal customer on items to be mailed, and a system that facilitates authentication of the printed indicia. When the postal customer purchases postage from the postal service, the postal service provides information which the postal customer uses to generate pseudo-random numbers associated with the respective units of postage. When the postal customer prints an indicium for a respective unit, it appends the associated pseudo-random number, which the postal service uses to authenticate the indicium. The pseudo-random numbers are generated using a methodology by which the postal customer can generate pseudo-random numbers for units which have been purchased, but not for units which have not yet been purchased. Each indicium represents an amount of information which can be printed using a one-dimensional barcode, instead of two-dimensional barcodes required in other systems. The postal service maintains a running record of the units of postage which have been used by the postal customer, and so the postal customer cannot use a unit for more than one indicium. Thus, devices such as the postal security device (xe2x80x9cPSDxe2x80x9d) are not needed by the postal customer, which provides for enhanced flexibility in printing the indicia.